Add PRESUBMIT checks for not required testharness expected files.

LayoutTests/PRESUBMIT.py

Index: LayoutTests/PRESUBMIT.py
diff --git a/LayoutTests/PRESUBMIT.py b/LayoutTests/PRESUBMIT.py
new file mode 100644
index 0000000000000000000000000000000000000000..93ea7285ba39b8b2a41264dab422d47e3e372e8c
--- /dev/null
+++ b/LayoutTests/PRESUBMIT.py
@@ -0,0 +1,39 @@
+# Copyright (c) 2013 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""LayoutTests/ presubmit script for Blink.
+
+See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
+for more details about the presubmit API built into gcl.
+"""
+
+
+def _CheckTestharnessResults(input_api, output_api):
+    expected_files = [f.AbsoluteLocalPath() for f in input_api.AffectedFiles() if f.LocalPath().endswith('-expected.txt') and f.Action() != 'D']
+    if len(expected_files) == 0:
+        return []
+
+    checker_path = input_api.os_path.join(input_api.PresubmitLocalPath(),
+        '..', 'Tools', 'Scripts', 'check-testharness-expected-pass')
+
+    args = [input_api.python_executable, checker_path]
+    args.extend(expected_files)
+    _, errs = input_api.subprocess.Popen(args,
+        stdout=input_api.subprocess.PIPE,
+        stderr=input_api.subprocess.PIPE).communicate()
+    if errs:
+        return [output_api.PresubmitError(errs)]
+    return []
+
+
+def CheckChangeOnUpload(input_api, output_api):
+    results = []
+    results.extend(_CheckTestharnessResults(input_api, output_api))
+    return results
+
+
+def CheckChangeOnCommit(input_api, output_api):
+    results = []
+    results.extend(_CheckTestharnessResults(input_api, output_api))
+    return results